The patent pending EZ Mount Track n' Roll is an interactive toy that keeps cats busy batting and swatting the two balls back and forth for hours. Can be used with other K&H EZ Mount products or on its own. Encourages exercise to keep pets healthy and fit. Attaches to any glass surface such as windows or sliding doors and most appliances.Mounts to any glass surface and most appliancesInteractive balls for hours of funPairs great with other K&H EZ Mount productsPerfect for glass doors, windows, or even on your fridgePatent pending